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Thu, 12 Mar 2026 06:39:19 -0700 (PDT) X-Received: by 2002:a2e:a991:0:b0:38a:69ae:ed76 with SMTP id 38308e7fff4ca-38a69af0e32mr23484641fa.8.1773322759293; Thu, 12 Mar 2026 06:39:19 -0700 (PDT) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 References: <20260311171209.9205-1-djeffery@redhat.com> <20260311171209.9205-2-djeffery@redhat.com> <932d4e59-395f-4022-a2de-874fdea778ac@acm.org> In-Reply-To: <932d4e59-395f-4022-a2de-874fdea778ac@acm.org> From: David Jeffery Date: Thu, 12 Mar 2026 09:39:06 -0400 X-Gm-Features: AaiRm50cC3-HopgnDbEpZBKck8Qg_3xXUFA0iihGZz6Xo1ScI6fOim-Jwqz1X4I Message-ID: Subject: Re: [PATCH 2/5] driver core: separate function to shutdown one device To: Bart Van Assche Cc: linux-kernel@vger.kernel.org, driver-core@lists.linux.dev, linux-pci@vger.kernel.org, linux-scsi@vger.kernel.org, Greg Kroah-Hartman , "Rafael J. Wysocki" , Danilo Krummrich , Tarun Sahu , Pasha Tatashin , =?UTF-8?B?TWljaGHFgiBDxYJhcGnFhHNraQ==?= , Jordan Richards , Ewan Milne , John Meneghini , "Lombardi, Maurizio" , Stuart Hayes , Laurence Oberman , Marco Elver Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Wed, Mar 11, 2026 at 2:03=E2=80=AFPM Bart Van Assche wrote: > > On 3/11/26 10:12 AM, David Jeffery wrote: > > +static void shutdown_one_device(struct device *dev) > > +{ > > + /* hold lock to avoid race with probe/release */ > > + if (dev->parent && dev->bus && dev->bus->need_parent_lock) > > + device_lock(dev->parent); > > + device_lock(dev); > > + > > + /* Don't allow any more runtime suspends */ > > + pm_runtime_get_noresume(dev); > > + pm_runtime_barrier(dev); > > + > > + if (dev->class && dev->class->shutdown_pre) { > > + if (initcall_debug) > > + dev_info(dev, "shutdown_pre\n"); > > + dev->class->shutdown_pre(dev); > > + } > > + if (dev->bus && dev->bus->shutdown) { > > + if (initcall_debug) > > + dev_info(dev, "shutdown\n"); > > + dev->bus->shutdown(dev); > > + } else if (dev->driver && dev->driver->shutdown) { > > + if (initcall_debug) > > + dev_info(dev, "shutdown\n"); > > + dev->driver->shutdown(dev); > > + } > > + > > + device_unlock(dev); > > + if (dev->parent && dev->bus && dev->bus->need_parent_lock) > > + device_unlock(dev->parent); > > + > > + put_device(dev->parent); > > + put_device(dev); > > +} > > Please keep the following code in the caller: > > if (dev->parent && dev->bus && dev->bus->need_parent_lock) > device_lock(dev->parent); > > if (dev->parent && dev->bus && dev->bus->need_parent_lock) > device_unlock(dev->parent); > > put_device(dev->parent); > put_device(dev); > > Additionally, please make sure that the caller is made compatible with > lock context analysis (see also > https://lore.kernel.org/all/20250206181711.1902989-1-elver@google.com/). > All that is required to make this code compatible with lock context > analysis is to organize it as follows: > > if (dev->parent && dev->bus && dev->bus->need_parent_lock) { > device_lock(dev->parent); > shutdown_one_device(dev); > device_unlock(dev->parent); > } else { > shutdown_one_device(dev); > } > This would also need to either grab another reference or move the reference drops since shutdown_one_device may drop the last reference the task owns to parent and dev. Since shutdown_one_device ends up called in 2 places in the next patch, perhaps would be best to split the bulk into another function, then have shutdown_one_device be a wrapper like: if (dev->parent && dev->bus && dev->bus->need_parent_lock) { device_lock(dev->parent); __shutdown_one_device(dev); device_unlock(dev->parent); } else { __shutdown_one_device(dev); } put_device(dev->parent); put_device(dev); David Jeffery